Esfand on Twitter: "CLARIFICATION FROM BLIZZARD ABOUT THE UBRS QUESTION. Loot Trading will only be in effect for content with a raid lockout. This means: Molten Core Onyxia Blackwing Lair Zul'Gurub AQ20
Classic WoW - Upper Blackrock Spire Guide (UBRS)
Blizzard Details WoW Classic Loot Trading; WOTLK-like Trading Will Only be Available in Raid Locked Content